Sheet transfer apparatus

Abstract

Apparatus for seizing and holding the trailing edge of a paper sheet for transfer and turn-over in a printing press. The sheet transfer cylinder is provided with a rotatable central shaft and a plurality of segment members arranged in spaced planes radial to the shaft in at least one set to provide a cylindrical circumferential surface for the paper. The apparatus comprises a first elongated rod extending through the segments of the set and journalled for rotation about its longitudinal axis, brackets fixed to the rod and extending toward the circumferential surface, and a second elongated rod journalled in the brackets for rotation about its longitudinal axis exterior of the segments. Gripper elements are carried by the second rod, and a counter-ledge or bar is carried by the brackets. The gripper elements are adapted to cooperate by mechanical action with the bar to seize the paper sheet on movement of the second rod.

What is claimed: 
     
       1. In a sheet transfer device for a printing press having a pair of frame sides, and a cylinder comprising a rotatable shaft journalled within said frame sides, and, a plurality of segment members fixed to said shaft, said segment members being spaced axially of each other and arranged in a pair of sets to have a common peripheral surface and leading and trailing edges, each of said segment sets having mechanical gripper means mounted for seizing the leading edge of said sheet, and apparatus for seizing the trailing edge of said sheet comprising, a first rod axially extending through the segments of said cylinder and journalled for rotation about its longitudinal axis, brackets fixed to said rod and extending outwardly adjacent the trailing edge of said peripheral surface, a second axially extending rod journalled within said brackets exterior of the segments of said cylinder to rotate about its longitudinal axis, gripper elements carried by said second rod, a bar mounted at the end of said brackets forming a ledge adapted to cooperate with said gripper elements, means for rotating said second rod to cause said gripper elements to seize the trailing edge of a paper sheet and means for rotating said first rod comprising an eccentric circular cam mounted on one of said sides, a first cam follower mounted on the one bracket adjacent said one side and engaging said cam to thereby cause said one bracket to pivot said first rod, an eccentric pin mounted on said cylinder adjacent said one bracket, a pull rod pivotally mounted on said cylinder adjacent said pin, and spring means connecting said pull rod and said first cam follower to adjustably urge said first cam follower against the first cam, said means being operable during the seizing of the leading edge of the sheet to move said brackets away from the adjacent trailing edge of said peripheral surface to thereby stretch said sheet over the peripheral surface of said segment set. 
     
     
       2. The apparatus according to claim 1 wherein the segments of one set of segments arranged diametrically opposite to the segments of the other set, the segments of each set alternating axially with the segments of the other set, said segments said segments being divided and fixed in part on a first tube and in part on a second tube, said first and second tubes being secured in spaced relation over said shaft for conjoint rotation therewith. 
     
     
       3. The apparatus according to claim 1 including adjustable stop means mounted on the segment adjacent said one bracket to engage said one bracket and limit the rearward movement thereof. 
     
     
       4. The apparatus according to claim 1 including a second circular cam mounted on said one side frame adjacent said one bracket, a two armed lever mounted at the end of said second rod adjacent said one side frame, a second cam follower mounted at the end of one arm of said lever and engaging said second circular cam, the other arm having on the one hand a rotatable pivot pin eccentrically mounted thereto and on the other hand a fixed pivot pin, a pull rod attached on one end to said fixed pivot pin and the other end to a spring urging the pull rod against the eccentrically mounted rotatable pin, said spring being secured to said end of said one bracket adjacent said second cam follower.